On March 2, about 1835 eastern standard time, a Cessna 150G, collided with a powerline then the ground during a forced landing following loss of engine power, near Miami, Florida. The flight originated about 1730, from Kendall-Tamiami Executive Airport. The certified flight instructor (CFI) stated that the engine began to run rough while performing airwork during an instructional flight. He elected to divert to a nearby airport where he performed an uneventful precautionary landing. While on the ground he performed an engine run-up and noticed a discrepancy with the left magneto. He operated the engine to a high rpm setting with the fuel/air ratio leaned in an effort to clear what he thought was lead fouled spark plugs, and reported that the left magneto drop was within limits (150 rpm). The CFI did not contact the operator to get assistance related to the precautionary landing, and elected to return to the original departure airport. During climbout, when the flight was 6-7 miles from the destination airport, the engine vibrations began and the rpm fluctuated 200 rpm, decreased to 2,000 rpm, then further decreased and remained at 300-400 rpm. He maneuvered the airplane towards a grass airstrip that he knew about, but because of the low light and visibility restriction, he flew past the airstrip. Due to the low altitude, he elected to land in a field perpendicular to the airstrip. While approaching the field, the airplane collided with powerlines then the ground, and nosed over. Disassembly of the left magneto revealed the point cam was worn, and the points exhibited erosion. Additionally, the coil tested out of limits; the condenser tested within specification.
What went wrong?
Our pilot in this report knew something was not right. We know this by his “pre-cautionary” landing made at another airport. This is where the flight should have been terminated.
Anytime you need to make a pre-cautionary landing to check something as serious as an engine vibration you should call it a day.
I understand the two pilots needed to get back to their home airport. But you have to think. “This airplane had just been acting squirrelly in the air, what makes you think I’m going to take it back up there?”
In flying it’s important to know when to trust your gut and when to trust the airplane.
